1. Field of the Invention
The invention relates to the field of photodynamic therapy, and in particular to devices and methods used for intrauterine photodynamic exposures.
2. Description of the Prior Art
Intrauterine light exposures for photodynamic therapy require exposure of drug impregnated tissue with a light intensity about an active threshold intensity and/or dosage. Given the large inner surface area of the uterine cavity the problem is to provide a delivery device which can provide an activating exposure to this area without leaving any portion of the inner surface unexposed or underexposed.
Grace et al., "Two-Piece Tip for Fiber Optic Catheter," U.S. Pat. No. 5,263,952 (1993), assigned to Spectranetics of Colorado Springs, Colo., shows a two-piece tip for a fiber optic catheter. The catheter provides for a more uniform illumination using a two-piece tip. The ends of the optical fibers do not extend parallel to the catheter axis, and in fact, the ends of the optical fibers may have exit surfaces which are perpendicular to the axis of the catheter. Alternatively, the ends of the optical fibers may have exit surfaces at an angle from the perpendicular. Referring specifically to FIG. 1, a light conveying cable 16 is terminated by a tip 28. Two-piece 28 is shown in FIG. 2 that is comprised of optical fibers 208 disposed to form an outer lumen 220 and an inner lumen 222. Thus, the light diffusing tip provides for a more uniform distribution of energy for photodynamic treatment.
Additional embodiments of the two-piece tip are shown in FIGS. 3-6. Grace simply shows a hollow cylindrical bundle of optic fibers disposed in a catheter and terminated between distal end clamping rings 204 and 206 in FIG. 2. The exit areas of the optic fibers may be perpendicular to the axis of the catheter as shown in FIG. 2, or angled in some manner as shown in the embodiments of FIGS. 3-6. The embodiments of FIGS. 4 and 5 show a angling of the optic fiber bundles that can be broadly considered as a Y form of divergence.
Grace fails to show a fiber array which is capable of springing outwardly in a body or uterine cavity to provide optimal illumination of the cavity or uterine walls.
Baker et al., "Optical Fiber Diffusion Tip for Uniform Illumination," U.S. Pat. No. 5,207,669 (1993), assigned to C. R. Bard, Inc. of Murray Hill, N.J., shows a laser balloon catheter assembly 12 in FIG. 1 which includes an optical fiber tip assembly 24 shown in greater detail in FIG. 2. Optical fiber 32 extends from connector 20 which is connected to an output of a laser source. Optical fiber 32 extends through flexible tube 10 and terminates in an optical fiber tip 24. Optical fiber tip assembly 24 is used to direct laser energy outwardly with the desired radiation pattern. Tip assembly 24, as seen in FIGS. 3 and 4, includes an extension of core 44, a thin cladding 48 and jacket 50. The characteristics of cladding 48, core 44 and jacket 50 are such as to provide uniform cylindrical diffusion or other desired pattern of radiation over the length of the entire diffusion tip 24. Baker has only a single catheter body and no means is provided for diverging diffusion segments.
Lundahl, "Intracavity Laser Phototherapy Method," U.S. Pat. No. 4,998,930 (1991), assigned to Phototherapeutic Systems, Martinez, Calif., describes a method of laser phototherapy using uniform irradiation of the inner walls of a hollow organ. The uniform distribution of energy is made possible by an optical laser fiber with isotropic diffuser tip. Diffuser tip 28 is located at the upper light output end of a light conducting fiber 27 best depicted in FIG. 2. Lundahl only shows a single irradiating diffusion segment.
Khoury, "Laser Catheter Diffuser," U.S. Pat. No. 5,151,096 (1992), assigned to Angiolaz, Inc. of Rockingham, Vt., shows the use of a laser catheter diffuser for activating photodynamic therapy in soft cancerous tissues. The diffuser includes an unclad fiber optic core with a reflective cap at a terminal end of the core. The reflective cap 14 is fixed to terminal end 20 of unclad fiber optic core 12 as shown in FIG. 2. The tip is surrounded by a diffuser matrix 16 with a pointed end 42 forming a collar 44 around an exterior edge 46 of reflective cap 14. In practice, the laser light travels along the laser catheter and is reflected from side to side within fiber optic core by cladding layer surrounding the core. Most of the light passes out of the core and diffuses away from the core through the diffuser matrix. The light that remains within the core reaches its terminal end and is reflected back by the reflective cap to diffuse out of the core via the diffuser matrix. By the means, a more uniform distribution of energy and a photodynamic therapy process is achieved. Khoury fails to show a branched fiber optic termination as the mechanism for light distribution in the photodynamic therapeutic application.
Narciso, Jr., "Laser Delivery System," U.S. Pat. No. 5,169,395 (1992), assigned to PDT Cardiovascular, Inc. of Goleta, Calif., shows another application of a catheter tip for delivering laser light for photodynamic therapy in combination with photoreactive molecules.
McCaughan, Jr., "Apparatus for Producing a Spherical Pattern of Light and Method of Manufacture," U.S. Pat. No. 4,693,556 (1987), assigned to Laser Therapeutics, Inc. of Worthington, Ohio, describes an apparatus for producing a spherical pattern of light in a radiating tip. As best shown in FIG. 2, the operation depends upon a scattering region 7 which is large in comparison to the source of light 6. Thus, when light emerges from the core of optic fiber 6, it encounters a strong scattering region 7. The light is repeatedly scattered in region 7 to give a uniform spherical pattern of radiation.
Means for diffusing the laser light delivered through the end of the catheter is well known. Radiation of body cavities by laser diffusers is also well known. Angled fiber optics and diffusing segments for fiber optics ends in catheters are generally described.
What is needed is some type of device or method for delivering light to the inner surface of a body cavity, such as the uterus, which will provide sufficient dosage and/or intensity of light to the entire inner surface of the cavity.